A massive 4-alarm fire broke out at a New York City church

A massive fire broke out at the Serbian Cathedral of Saint Sava in New York City on Sunday evening.

It is unclear whether anyone was in the building or how the fire started.

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Massive fire destroys NYC church

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A massive 4-alarm fire broke out at a New York City church

Massive fire inside church on West 25th Street in NYC.

Last night I watched a beautiful Landmark burn to the ground. The Serbian Orthodox Cathedral of St. Sava was a beautiful, quiet and safe place. It's hard to believe I was inside just 3 hours before the blaze... I'm glad no one was hurt but having such a beautiful building burn down before your eyes is heartbreaking. So much artwork lost. My heart goes out to members of the congregation. Now there's nothing left but bones of the building.

The fire broke out around 6:49 p.m., according to the FDNY. It quickly spread to three alarms, and by 8 p.m. the fire had spread to four alarms.

The FDNY was on the scene with about 170 firefighters.

The number of alarms in the FDNY fire-alarm rating system corresponds to the number of firefighters required to respond to the fire. For a two-alarm fire, the FDNY dispatches 25 units and 106 firefighters; a three-alarm fire means 33 units and 138 firefighters; a four-alarm fire means 39 units and 168 firefighters, according to Slate.